Glazing cast iron



Patented Apr. 21, 1925.

PATENT OFFICE.

WILLIAM E. HOKE, OF BALTIMORE, MARYLAND.

GLAZING- CAST IRON.

No Drawing.

To all whom it may concern:

Be it known that I, WILLIAM E. I-IoKE, a citizen of the United States, residing at Baltimore, in the county of Baltimore and State of Maryland, have invented certain new and useful Improvements in Glazing Cast Iron, of which the following is a specification.

My invention relates to the production of wear resisting surfaces on cast-iron, and is especially applicable to the cast-iron cylinders of automobile engines.

The inner surfaces of these cylinders are usually ground with emery wheels in suitable grinding machines, and I have discovered that the grinding may be so conducted that a hard, smooth, glazed, durable wearing surface is imparted to these surfaces while they are being ground.

The controlling factors'in the production of this result are the grade of abrasive, the speed at which the grinding is conducted, the pressure applied to the grinding wheel, and the hardness of the abrasive. These factors are so combined and controlled that the frictional heat produced by the grinding is increased to a considerable degree above that produced by grinding according to acceptedmethods.

Where the usual types of grinding wheels are used, the pressure applied may be reduced to the point which the grains of emery or other abrasive, do not break away from the wheel, as in ordinary grinding, with the result that the grinding wheel is glazed, and the effect on the metal surface is one of burnishing, rather than grinding, with the resultant production of a'hard glazed surface on the cast-iron.

A like result may be obtained by feeding the work at a speed lower than that used in nomal grinding; or a grinding wheel of finer grain than that which would normally be selected may be used; or a wheel of abnormally hardstructure, may be selected; or the wheel can be glazedby the use of heavy grease.

I prefer to use an abrasive of a 'very' tough nature, which would tend to polish Application filed March 30, 1921. Serial No. 457,104.

the surface of the abrasive grains before their particles would break away. Such hard, tough abrasives'comprise those made of certain grades of alumina. Using such a hard, tough wheel with a slow feed and a copious flow of cooling liquid, the maximum hardness of cast-iron surface is obtained.

A surface of the kind described may be produced after the grinding has been effected in the usual manner, but the use of, two different grades of grinding wheel, one.

for grinding and another for hardening, would, in practice be difiicult.

Therefore, I prefer to so carry out the grinding operation that when the usual grinding has been effected, thepressure and feed of the work are altered to produce the eflect above described.

The hardening of the surface, in the manner described, appears to beeifected by the hot burnishing action of the grinding tool and also by the heating and quenching action resulting from the intense local heating due to the action of the abrasive following by the practically instantaneous cooling effect of the cooling liquid.

production of a cast-iron surface of such hardness that it can barely be touched by a file or scraper.

While I have described my invention as Whatever be the cause, the result is the which a cooling liquid is applied to the surface and the tool.

In testimony whereof, I afiix my signature.

WILLIAM E. Home. 

